understanding par

To really determine EXACTLY what wavelengths are absorbed by any given coral is next to impossible... But despite this fact, a reseacher by the name of Dana riddle has published a series of articles that, in my opinion, are revolutionary for the field. You can try to find them but if you have trouble I will supply the links when I am around my computer later tonight.

Hey crank, to the best of my knowledge nothing has been officially published on this yet. The excerpt above is from a personal article that I have written myself but it is not "officially published" anywhere. My basis for this stance is mainly from working with Sanjay, analyzing research from dana riddle, applying my background in biochemistry and very limited physics, and personal observations my own tanks and also in many experienced reefers' tanks.

I guess I technically didn't do any testing myself but more of compiling data then applying my knowledge where these fields overlap to come to this conclusion.
I'll get those links from dana's research tonight.

 

What about horizontal transfer of zooxnathelle to adapt to various light environments? This has been suggested in Little et al 2004 and by others. Do you think that this is not likely in a closed system? Or that there are still l limitations to what spectrum a cnidarian can utilize regardless of the hosted algae? If this does occur, it would mean par may be a somewhat better metric than you suggest, as the host would have more ability to adapt to various spectrum, as long as sufficient intensity is provided. Of course there isn't much data, on this, so, it's speculation. However, I think to say that it doesn't happen, is also speculation. PAR or PUR may not be a great metrics, but they are functionally useful and are probably the best metrics we have without further research.

 

I remember this write up! I turned in my paper and got an 100% on it, BTW Dingo. Thanks a lot for your help.

Light output required for corals is a very in-depth subject, for sure. Damon, it does make sense to suggest that the wavelength of light being used and output are not the same. The coral will absorb the wavelength it needs, use it for photosynthesis to produce glucose and reflect that unused light as a new wavelength,which is the color we see that coral as.

I read everything you wrote again on the post and wonder what you think determines the best light(overall) for an SPS tank, if PAR is not a good measurement? I am partially having trouble reading your thoughts. I believe I have asked this before, but I don't recall your thoughts on it. PAR is not the best measurement, so when you pick lighting, how do you decide on what light(s) to go with?

 

this would basically be something morphing color to adapt to the light?

 

Yes, if horizontal transfer of Zoox occurred, then this would mean the color(s) of the coral would be morphed, containing two or more different nm wavelengths of zoxx in the corals' tissue.

 

I read everything you wrote again on the post and wonder what you think determines the best light(overall) for an SPS tank, if PAR is not a good measurement? I am partially having trouble reading your thoughts. I believe I have asked this before, but I don't recall your thoughts on it. PAR is not the best measurement, so when you pick lighting, how do you decide on what light(s) to go with?[/QUOTE]

You may be having trouble reading my thoughts because I have plenty of trouble with them myself . I may have said par is not the best measurement of light, but I think it's pretty obvious that I am no authority on the subject and am just trying to form my own opinion about how to rate this stuff. Par and Pur still seem like general light measurements and it seems the people that really know are getting more specific about their light. I'm still unclear on uv light too (that is out side par right?) and what is needed for our tanks. I'm just saying that a more specific statement about the wavelength and power (not really sure the correct term here, but I think you know what I'm saying) helps me compare lights more than just par. I am just switching over from following what I've seem people do and has worked for them to trying to make my own opinions of everything, so I have not compared too many bulbs specifically. I just went with some ati t5s as recommended, but now that I'm thinking I might want something different (I really like a lot of things about led) I feel I need to understand things better. I have no clue what determinants the best light for a sps tank, because I have very little experience with sps dominated tanks.

 

Whoops...that was directed at Dingo. But I'll talk to you too.

Wavelength would be the correct term you were looking for. As in, wavelength of light, or to be within a certain nm(nano-meter) range. I know blues are best for color while the more white will promote good growth. I want a happy medium...great growth and great color(can I get that? I am looking at these bulbs over my 29g tank which I want to be dominately SPS...

Hands-on Preview of Orphek's PR-25 PAR38 LED Spotlight - Captive Aquatics: An Aquarium and Ecology Blog

 

Horizontal transfer does happen in our tanks but it is very limited... Transfer in our tanks is not a function of adaptation for survival, but more adaptation for more available energy. The diversity of the free floating zoox in our tanks is very low compared to the oceans. Over years and years you can increase your diversity but this is a very slow process haha. In my experience, I have only ever had one acro that expelled it's zoox and lived for an extended period of time. This acro has been white for 3 months now and has still not decided to take up any of the available zoox in my tank... I'm honestly surprised that it is getting enough energy from just the polyps to live this long.

Now I have to speak in generalizations here because each coral's photosystem is different, there are even (sometimes vast) variations between the same species. So generally speaking, a coral will have the primary photosystem that produces a majority of the energy/nutrients used. From this you can determine around the wavelength that each and every coral utilizes the most.

I'm not here to tell people they are wrong or to say that I am absolutely right... But if your coral uses mostly blue light in it's photosystems, then supplying a bulb that has a high PAR will not necessary mean that the coral will be happy. If the bulb supplies a lot of blue light to produce that PAR then the coral will be happy, however if a majority of the PAR is from a red wavelength then the coral will not be happy. Also, if the PAR is low it does not mean the bulb is bad either, it could just mean that the photons are mainly distributed across the highly used wavelengths... This is where the spectral analysis tells us much more about the light being put out than the PAR.

 

Thank you! So what I'm saying is that you have to look at the quantity of photons released for each nm. This is usually a graph of spectral irradiance vs. Wavelength.

Damon- I can talk ALL day about UV lol... Unfortunately this is one place where a few people disagree with me. Anyways, it is too hard for me to follow this thread via my cell phone haha. I will get on my computer tonight and explain UV and any other questions that come up.